Telecommunications systems, cable television systems and data communication networks use optical networks to rapidly convey large amounts of information between remote points. In an optical network, information is conveyed in the form of optical signals through optical fibers. Optical fibers comprise thin strands of glass capable of transmitting the signals over long distances with very low loss.
Optical networks often employ wavelength division multiplexing (WDM) or dense wavelength division multiplexing (DWDM) to increase transmission capacity. In WDM and DWDM networks, a number of optical channels are carried in each fiber at different wavelengths or frequencies. Network capacity can be defined based on the number of wavelengths, or channels, in each fiber, and the bandwidth, or size, of the channels.
Particular optical networks may include Bi-Directional Line Switched Ring (BLSR) capability enabling the switching of optical traffic to a protection path if a failure or error occurs in a working path carrying the optical traffic. Thus, the working path is monitored for errors. Some networks monitor the optical fibers between network elements of the protection path for line cuts or errors in the optical components.